Method for treating waste lubricating oil wastewater

Abstract

The present application relates to the field of wastewater treatment, and discloses a method for treating waste lubricating oil wastewater, which comprises the following steps: 1) performing oil removal treatment on the waste lubricating oil wastewater, so that the oil content in the waste lubricating oil wastewater after the oil removal treatment is less than or equal to 20% of the oil content in the waste lubricating oil wastewater; 2) adjusting the pH value of the waste lubricating oil wastewater after the oil removal treatment to 7-14; and 3) performing catalytic wet oxidation on the effluent of step 2), wherein the COD of the influent of the catalytic wet oxidation is less than or equal to 100000 mg / L by mixing the effluent of the catalytic wet oxidation with the effluent of step 2). cr The method provided by the present application can efficiently remove COD cr , ammonia nitrogen and halides with high biological toxicity in the waste water, improve the biodegradability of the waste water, and is particularly suitable for treating waste water of a waste lubricating oil hydrogenation regeneration device.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment, and more specifically to a method for treating waste lubricating oil wastewater. Background Technology

[0002] With the rapid development of the automotive and machinery industries, the demand for lubricating oil has been increasing year by year, and the disposal of waste lubricating oil has attracted great attention within the industry. Recycling and reusing waste lubricating oil through regeneration technology can effectively reduce the consumption of my country's petroleum resources and reduce pollution to the ecological environment. There are two main reasons for the generation of waste lubricating oil: first, impurities such as water, dust, and metal powder are introduced during use; second, the lubricating oil oxidizes and deteriorates over long-term use, resulting in poor viscosity-temperature properties, reduced oxidation stability, and increased corrosiveness.

[0003] Currently, waste lubricating oil regeneration technologies include acid washing, solvent refining, adsorption, hydrorefining, and membrane separation. Hydrorefining technology comprises three parts: hydrotreatment, hydrodepletion, and refining. This method can improve the viscosity-temperature and oxidation stability of lubricating oil, lower its pour point, and improve its color. However, the hydrorefining process inevitably generates highly toxic, high-COD organic wastewater. Besides oil (floating oil and emulsified oil), this wastewater also contains highly biotoxic, odorous, and water-soluble substances such as phenols, ethers, nitrogen heterocycles, sulfides, organic amines, and halides. These substances must undergo rigorous water treatment processes before being discharged into the environment.

[0004] CN101279786A relates to a method for treating oily wastewater, particularly for treating oily wastewater from oil refineries and oilfields. First, a demulsifier A is added to the oily wastewater. After a demulsification reaction, a flocculant B is then added. Oily wastewater treated by this method, especially oily wastewater from oil refineries and oilfields, can meet the process parameters required for subsequent biochemical treatment. This method is suitable for treating wastewater with relatively good biodegradability, but not for wastewater with high biotoxicity or high COD.

[0005] Traditional methods for treating oily wastewater, including biological treatment and demulsification, are insufficient to effectively remove COD and ammonia nitrogen (combined nitrogen existing in the form of ammonia or ammonium ions, i.e., free ammonia (NH3) and ammonium ions (NH4) in the wastewater). + The wastewater contains nitrogen in the form of nitrogen oxides and highly biotoxic halides (such as 2-chloroethanol and ethyl 2-chloroacetate). Therefore, it is imperative to develop an effective wastewater treatment technology for waste lubricating oil hydrogenation regeneration units. Summary of the Invention

[0006] The purpose of this invention is to overcome the problem of unsatisfactory waste lubricating oil wastewater treatment effect in the existing technology, and to provide a method for treating waste lubricating oil wastewater.

[0007] The inventors of this invention discovered in their research that treating waste lubricating oil wastewater using catalytic wet oxidation under specific pH conditions and then recycling the effluent from the catalytic wet oxidation process can achieve excellent treatment results. Therefore, to achieve the above objectives, this invention provides a method for treating waste lubricating oil wastewater, comprising:

[0008] 1) Mix waste lubricating oil wastewater with demulsifier to demulsify; then mix the demulsified wastewater with flocculant to remove floating oil, so that the oil content in the wastewater after removing floating oil is less than 20% of the oil content in the waste lubricating oil wastewater.

[0009] 2) Adjust the pH of the wastewater after oil removal to 7-14;

[0010] 3) The effluent from step 2) is subjected to catalytic wet oxidation, wherein the effluent from the catalytic wet oxidation is mixed with the effluent from step 2) to reduce the COD of the influent to the catalytic wet oxidation. cr Less than or equal to 100,000 mg / L;

[0011] 4) Optionally, the effluent from step 3) may be subjected to biological treatment.

[0012] The method provided by this invention can efficiently remove ammonia nitrogen and COD from wastewater. cr It contains highly biotoxic halides, which improve the biodegradability of wastewater, and is particularly suitable for the treatment of wastewater from waste lubricating oil hydrogenation regeneration units. Detailed Implementation

[0013] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0014] This invention provides a method for treating waste lubricating oil wastewater, characterized in that the method includes:

[0015] 1) Mix waste lubricating oil wastewater with a demulsifier to demulsify; then mix the demulsified wastewater with a flocculant to remove floating oil, so that the oil content in the wastewater after oil removal is less than 20% of the oil content in the waste lubricating oil wastewater;

[0016] 2) Adjust the pH value of the wastewater after oil removal to 7-14 (preferably 8-12, such as 8, 8.5, 9, 9.5, 9.8, 10, 11, 12 or any value between the above values);

[0017] 3) The effluent from step 2) is subjected to catalytic wet oxidation, wherein the effluent from the catalytic wet oxidation is mixed with the effluent from step 2) to reduce the COD of the influent to the catalytic wet oxidation. cr Less than or equal to 100,000 mg / L;

[0018] 4) Optionally, the effluent from step 3) may be subjected to biological treatment.

[0019] According to the present invention, based on the weight of the waste lubricating oil wastewater, the weight amount of the demulsifier is 50-500 ppm (e.g., 55, 60, 90, 100, 110, 200, 300, 350, 450 ppm or any value between the above). The demulsifier can be any type of demulsifier commonly used in the art, but is preferably selected from nonionic demulsifiers. More preferably, the nonionic demulsifier is selected from at least one of SP-type demulsifiers, AP-type demulsifiers, AE-type demulsifiers, and AR-type demulsifiers. The main component of the SP-type demulsifier is polyoxyethylene polyoxypropylene octadecyl alcohol ether. The AP-type demulsifier is a polyoxyethylene polyoxypropylene polyether with polyethylene polyamine as an initiator, with the molecular structural formula: D(PO)x(EO)y(PO)zH, where: EO-polyoxyethylene; PO-polyoxypropylene; D-polyethylene polyamine; x, y, z-degree of polymerization. AE-type demulsifiers are polyoxyethylene and polyoxypropylene polyethers initiated by polyethylene polyamines. Unlike AP-type demulsifiers, AE-type demulsifiers are two-stage polymers with small molecules and short branches. Their molecular structure is: D(PO)x(EO)yH, where: EO - polyoxyethylene; PO - polyoxypropylene; D - polyethylene polyamine; x, y - degree of polymerization. AR-type demulsifiers are oil-soluble, non-ionic demulsifiers polymerized from alkylphenol resin (AR resin) with polyoxyethylene and polyoxypropylene. They have an HLB value of approximately 4-8 and a low demulsification temperature of 35-45℃. Their molecular structure is: AR(PO)x(EO)yH, where: EO - polyoxyethylene; PO - polyoxypropylene; AR - resin; x, y, z - degree of polymerization.

[0020] According to the present invention, based on the weight of the waste lubricating oil wastewater, the weight amount of flocculant is 10-400 ppm (e.g., 15, 25, 30, 35, 90, 100, 110, 140, 160, 200, 300, 350 ppm or any value between the above). The flocculant can be any flocculant commonly used in the art for flocculating and removing floating oil, but preferably, the flocculant includes iron-containing flocculants. Using iron-containing flocculants, especially iron-containing inorganic flocculants, can further improve the ammonia nitrogen removal rate of the wastewater. More preferably, the flocculant is selected from organic flocculants and iron-containing inorganic flocculants in a weight ratio of 0.1-10 (e.g., 0.4, 0.5, 0.6, 0.9, 1, 1.2, 1.5, 2, 2.5, 3, 5, 7, 9 or any value between the above).

[0021] More preferably, the organic flocculant is selected from at least one of polyacrylamide, sodium polyacrylate, polyvinylpyridine salt, polyethyleneimine, and sodium carboxymethyl cellulose.

[0022] More preferably, the iron-containing inorganic flocculant is selected from at least one of polyferric chloride, polyferric sulfate, polyferric chloride sulfate, and polyphosphoric ferric chloride.

[0023] According to the present invention, there are no special requirements for the operating conditions of demulsification and removal of floating oil in step 1), and room temperature can be used.

[0024] According to the present invention, in step 2), a hydroxide is used to adjust the pH value of the wastewater after oil removal to a specific value. The hydroxide can be a base conventionally used in the art, such as an alkali metal hydroxide and / or an alkaline earth metal hydroxide; preferably, the hydroxide is selected from at least one of sodium hydroxide, potassium hydroxide, and calcium hydroxide. Such adjustment of the pH value of the wastewater after oil removal is particularly beneficial for further improving the biodegradability of the wastewater.

[0025] According to the present invention, the volume ratio of the effluent from the catalytic wet oxidation to the effluent from step 2) can be 0.5 to 5, preferably 0.6 to 4.

[0026] According to the present invention, the method may further include a step of biochemically treating the effluent from step 3) so that the wastewater can be reused. There are no special requirements for the biochemical treatment method, which will not be described in detail here.

[0027] According to the present invention, the catalytic wet oxidation can be performed by catalytically wet oxidizing the effluent from step 2) in the presence of a heterogeneous catalyst and oxygen. The heterogeneous catalyst may include a support and an active component. For better treatment results, preferably, the active component is selected from at least two of oxides of Group IB, Group VB, Group VIB, Group VIIB, and Group VIII metals, and the support is selected from at least one of oxides of Group IIA, Group IIIA, Group IVA, and Group IVB metals.

[0028] In a preferred embodiment of the present invention, based on the total weight of the heterogeneous catalyst, the content of the support can be 85-95% by weight (e.g., 85% by weight, 86% by weight, 87% by weight, 88% by weight, 90% by weight, 95% by weight or any value between the above values), and the content of the active component can be 5-15% by weight (e.g., 8% by weight, 9% by weight, 9.5% by weight, 10% by weight, 12% by weight, 13% by weight, 14% by weight, 15% by weight or any value between the above values).

[0029] The heterogeneous catalyst of this invention can achieve good catalytic wet oxidation performance even without the use of precious metals. Therefore, based on the total weight of the heterogeneous catalyst, the content of precious metals in the heterogeneous catalyst can be less than or equal to 0.5% by weight, preferably less than or equal to 0.1% by weight, and more preferably free of precious metals. The precious metals are common precious metals in the art, including gold, silver, and platinum group metals (ruthenium, rhodium, palladium, osmium, iridium, platinum).

[0030] In a preferred embodiment of the present invention, the XRD pattern of the heterogeneous catalyst has a characteristic peak at 2θ = 37° ± 0.2.

[0031] In a preferred embodiment of the present invention, the active component is selected from at least two of the oxides of Cu, Mn, Co, Fe, Mo, and Nb. In a preferred embodiment, the active component can be any two, three, four, five, or six of the above metal oxides. However, in another preferred embodiment, the active component is selected from oxides of Group VIIB metals (especially Mn) and oxides of Group VB metals (especially Nb), and the content of the oxides of Group VIIB metals and the oxides of Group VB metals is such that the molar ratio of Group VIIB metals to Group VB metals is 1:(0.09-5), more preferably 1:(0.1-3), such as 1:0.1, 1:0.2, 1:0.3, 1:0.5, 1:0.6, 1:1, 1:1.5, 1:2, 1:2.5, or any value between the above values.

[0032] In a preferred embodiment of the present invention, the support is selected from at least one of oxides of Ca, oxides of Mg, oxides of Al, oxides of Si, oxides of Ti, and oxides of Zr. In a preferred embodiment, the support can be one or more of the above oxides. However, in another preferred embodiment, the support is selected from oxides of Group IIA metals (especially Mg) and oxides of precursors of Group IIIA metals (especially Al), and the content of oxides of Group IIA metals and oxides of Group IIIA metals is such that the molar ratio of Group IIA metals to Group IIIA metals is 1:(5.5-55), more preferably 1:(10-25), such as 1:11, 1:12, 1:12.5, 1:13, 1:15, 1:16, 1:17, 1:20, 1:21, 1:22, 1:24, or any value between the above values.

[0033] This invention also relates to a method for preparing a heterogeneous catalyst, the method comprising:

[0034] Step S1: Mix the carrier precursor with an optional molding aid, and perform molding, first drying and first calcination in sequence to obtain the carrier;

[0035] Step S2: Load the active component onto the support obtained in step S1. It is understood that the method for treating waste lubricating oil wastewater of the present invention may further include the step of preparing the heterogeneous catalyst according to the above steps. It is understood that the method for treating waste lubricating oil wastewater of the present invention may include the step of first preparing the heterogeneous catalyst according to the aforementioned steps.

[0036] According to the preparation method of the present invention, the carrier precursor can be selected according to the type of the aforementioned carrier. For example, the carrier precursor can be selected from at least one of the following: oxides, salts, and hydroxides of Group IIA metal elements (preferably Ca and / or Mg), oxides, salts, and hydroxides of Group IIIA metal elements (preferably Al), oxides, salts, and hydroxides of Group IVA elements (preferably Si), and oxides, salts, and hydroxides of Group IVB metal elements (preferably Ti and / or Zr). As previously mentioned, more preferably, the carrier precursor is selected from Group IIA metal element precursors (especially Mg) and Group IIIA metal element precursors (especially Al), and the amount of Group IIA and Group IIIA metal element precursors is such that the molar ratio of Group IIA metal element to Group IIIA metal element is 1:(5.5-55), more preferably 1:(10-25), such as 1:11, 1:12, 1:12.5, 1:13, 1:15, 1:16, 1:17, 1:20, 1:21, 1:22, 1:24, or any value between the above values. The Mg precursor may be selected from at least one of magnesium carbonate, magnesium oxide, magnesium hydroxide, magnesium acetate, magnesium sulfate, and magnesium nitrate. The Al precursor may be selected from at least one of alumina, aluminum hydroxide, boehmite, and aluminum nitrate. Among them, alumina can be selected from γ-Al2O3, such as those with an average particle size of 30-50 nm and a specific surface area of ​​60-65 m². 2 / g of γ-Al₂O₃. The specific surface area of ​​pseudoboehmite can be 250–300 m² / g. 2 / g.

[0037] According to the preparation method of the present invention, there are no particular requirements on the amount of the molding aid. For example, relative to 100g of the carrier precursor, the amount of the molding aid can be 0.5-10g (e.g., 1g, 2g, 2.5g, 2.7g, 2.8g, 3g, 3.2g, 4g, 5g, 6g, 8g, 9g, or any value between the above). The molding aid can be a commonly used molding aid in the art, but preferably, the molding aid is selected from inorganic acids, more preferably at least one of sulfuric acid, hydrochloric acid, phosphoric acid, and nitric acid. The molding method can be extrusion molding.

[0038] According to the preparation method of the present invention, the conditions for the first drying may include: a drying temperature of 20 to 100°C, preferably 40 to 60°C, and a drying time of 4 to 48 hours, preferably 12 to 48 hours.

[0039] According to the preparation method of the present invention, the conditions for the first calcination may include: a calcination temperature of 500–1000°C, preferably 700–850°C (e.g., 700°C, 740°C, 745°C, 750°C, 755°C, 760°C, 780°C, 800°C, 820°C, 850°C, or any value between the above values), and a calcination time of 1–12 h, preferably 2–10 h (e.g., 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 6 h, 7 h, 8 h, or any value between the above values). The first calcination can be carried out in an air atmosphere.

[0040] According to the preparation method of the present invention, the active component can be loaded onto the carrier obtained in step S1 using methods commonly found in the art, such as impregnation, spraying, etc. The preferred method for loading the active component onto the carrier obtained in step S1 is to impregnate the carrier with an impregnation solution containing an active component precursor, followed by a second drying and a second calcination.

[0041] More preferably, the active component precursor can be selected according to the type of the aforementioned active component. For example, the active component precursor can be selected from at least two of the following: oxides, salts, and hydroxides of Group IB metal elements (preferably Cu); oxides, salts, and hydroxides of Group VB metal elements (preferably Nb); oxides, salts, and hydroxides of Group VIB metal elements (preferably Mo); oxides, salts, and hydroxides of Group VIIB metal elements (preferably Mn); and oxides, salts, and hydroxides of Group VIII metal elements (preferably Co and / or Fe). As previously mentioned, more preferably, the active component precursor is selected from Group VIIB metal element (especially Mn) precursors and Group VB metal element (especially Nb) precursors, and the amount of Group VIIB metal element precursors and Group VB metal element precursors is such that the molar ratio of Group VIIB metal element to Group VB metal element is 1:(0.09-5), more preferably 1:(0.1-3), such as 1:0.1, 1:0.3, 1:0.5, 1:0.6, 1:1, 1:1.5, 1:2, 1:2.5 or any value between the above values. The Mn precursor can be selected from at least one of potassium permanganate, manganese chloride, manganese sulfate, manganese nitrate and manganese acetate. The Nb precursor can be selected from at least one of niobium pentoxide, niobium oxalate, niobium chloride, niobium hydroxide and niobium ethoxide.

[0042] More preferably, the impregnation conditions include: an impregnation temperature of 20–80°C, preferably 40–80°C, and an impregnation time of 4–48 h, preferably 8–24 h. There are no particular requirements regarding the concentration of the active component precursor in the impregnation solution; impregnation can be either equal-volume or excessive.

[0043] More preferably, the conditions for the second drying include: a drying temperature of 20–120°C, preferably 60–80°C, and a drying time of 4–48 h, preferably 8–24 h.

[0044] More preferably, the conditions for the second calcination include: a calcination temperature of 300–700°C, preferably 400–550°C (e.g., 400°C, 440°C, 445°C, 450°C, 455°C, 460°C, 480°C, 500°C, 520°C, 550°C, or any value between the above values), and a calcination time of 1–12 h, preferably 2–6 h (e.g., 3 h, 3.5 h, 3.8 h, 4 h, 4.2 h, 4.5 h, 5 h, 6 h, or any value between the above values). The second calcination can be carried out in an air atmosphere.

[0045] More preferably, in order to make the active component more uniformly dispersed on the support and thereby further improve the catalytic oxidation activity of the heterogeneous catalyst, the impregnation is carried out in the presence of an organic acid. Preferably, the organic acid is selected from at least one of C1-C6 monocarboxylic acids and / or C1-C6 polycarboxylic acids, such as formic acid, acetic acid, propionic acid, succinic acid, tartaric acid, and citric acid; more preferably, it is selected from C1-C3 monocarboxylic acids and C3-C5 dicarboxylic acids (especially hydroxylated C3-C5 dicarboxylic acids) in a weight ratio of 1:(0.1-10); most preferably, it is selected from acetic acid and tartaric acid in a weight ratio of 1:(0.5-4.5) (e.g., 1:0.55, 1:0.6, 1:0.7, 1:1, 1:2, 1:3, 1:3.5, 1:3.8, 1:4, 1:4.5, or any value between the above values). Preferably, the weight ratio of the carrier to the organic acid is 100:(0.5-10), such as 100:1, 100:3, 100:4, 100:4.5, 100:5, 100:5.5, 100:6, 100:7, 100:8, 100:9 or any value between the above values.

[0046] According to the present invention, the conditions for the catalytic wet oxidation may include: a reaction temperature of 120–250°C and a reaction pressure of 1–7 MPa. Preferably, the conditions for the catalytic wet oxidation include: a reaction temperature of 160–220°C and a reaction pressure of 2.5–4.5 MPa. Preferably, the conditions for the catalytic wet oxidation further include: influent COD cr The concentration is 20,000–100,000 mg / L, more preferably 40,000–80,000 mg / L. Influent COD cr The COD of the influent can be controlled by mixing it with the effluent from catalytic wet oxidation. crWithin the aforementioned preferred range, the wastewater retention time can be further shortened, such that the conditions for the catalytic wet oxidation include: a wastewater retention time of 0.5–5 h, more preferably 1–3 h. However, those skilled in the art will understand that if COD cr If the COD remains high, the effluent quality of the catalytic wet oxidation process can be controlled by extending the wastewater retention time. The inventors of this invention have discovered that catalytic wet oxidation under the above conditions achieves superior treatment results, reducing COD levels. cr The ammonia nitrogen removal rate is higher. In step (3), the effluent from the catalytic wet oxidation can be the effluent from waste lubricating oil wastewater that has undergone conventional catalytic wet oxidation treatment, or it can be the effluent from catalytic wet oxidation according to the process of this invention. It will be understood by those skilled in the art that, according to the method of this invention, when the effluent from the catalytic wet oxidation produced by the process of this invention is insufficient for step 3), the effluent from catalytic wet oxidation of other processes and / or soft water can be mixed with the effluent from step 2) to reduce the COD of the influent to the catalytic wet oxidation. cr The above requirements must be met.

[0047] According to the present invention, in step 1), the oil content in the wastewater after oil removal is ≤500mg / L, preferably ≤200mg / L. If the oil content of the wastewater is high, the wastewater can be treated to remove the oil using methods commonly used in the art. For example, the oil content of the influent can be controlled by filtration after demulsification and flocculation, and the pore size of the filter membrane can be 0.5-2μm.

[0048] According to the present invention, the method is particularly applicable to the treatment of waste lubricating oil wastewater containing halides. Therefore, the waste lubricating oil wastewater may contain halides, such as haloalcohols and / or haloesters, preferably 2-chloroethanol and / or ethyl 2-chloroethanol. The content of halides in the waste lubricating oil wastewater can be 50-2000 mg / L. Further, the content of 2-chloroethanol in the waste lubricating oil wastewater can be 50-2000 mg / L (e.g., 300, 350, 400, 450, 600, 800, 1000, 1500, 1600, 1700, 1800 mg / L or any value between the above). Further, the content of ethyl 2-chloroacetate in the waste lubricating oil wastewater can be 50-2000 mg / L (e.g., 300, 600, 800, 1000, 1100, 1300, 1400, 1500, 1600, 1700, 1800 mg / L or any value between the above). The COD of the waste lubricating oil wastewater... cr The concentration can be 100,000-300,000 mg / L. The ammonia nitrogen concentration in the waste lubricating oil wastewater can be 500-2000 mg / L. The BOD5 / COD ratio of the waste lubricating oil wastewater... crIt can range from 0.02 to 0.08. Among them, "COD" cr "Chemical Oxygen Demand (BOD)" refers to the amount of reducing substances in a water sample that need to be oxidized, measured as the oxygen equivalent using potassium dichromate as the oxidant. "BOD" refers to Biochemical Oxygen Demand (BOD), which is the amount of dissolved oxygen consumed during the biochemical reactions of microorganisms decomposing biodegradable organic matter in water under certain conditions. If the biochemical oxidation process takes five days, it is called the five-day biochemical oxygen demand (BOD5). The ratio of BOD5 to COD is also mentioned. cr The value reflects the biodegradability of wastewater; the larger the value, the easier it is for waste lubricating oil wastewater to be biodegraded.

[0049] According to a preferred embodiment of the present invention, the waste lubricating oil wastewater is wastewater from a waste lubricating oil hydrogenation regeneration unit. Generally, the oil content of the waste lubricating oil hydrogenation regeneration unit wastewater is 2000-5000 mg / L, chloride accounts for 5-8% by weight of total organic pollutants, phenol accounts for 6-10% by weight of total organic pollutants, ether accounts for 65-80% by weight of total organic pollutants, alcohol accounts for 7-15% by weight of total organic pollutants, and ester accounts for 1-5% by weight of total organic pollutants.

[0050] The present invention also relates to a method for removing halides (particularly 2-chloroethanol and 2-chloroethyl acetate) from waste lubricating oil wastewater according to the method described above.

[0051] The present invention will be described in detail below through examples. In the following examples, the demulsifier and flocculant were purchased from Guangzhou Xiaozhong Environmental Protection Technology Co., Ltd. and Gongyi Jinyuan Chemical Co., Ltd., respectively; XRD analysis was performed using a German Bruker D8 Advance X-ray diffractometer (XRD), with a Cu target, Kα ray source, Links detector, tube voltage 40kV, tube current 40mA, scan rate 5° / min, and 2θ 10~80°; the elemental composition of the catalysts obtained in the examples was analyzed by X-ray fluorescence spectroscopy. The elemental composition obtained by X-ray fluorescence spectroscopy was basically close to the elemental composition of the feed, so it will not be shown again; the oil content was determined according to the method of GB / T 12152-2007 "Determination of Oil Content in Boiler Water and Cooling Water" on a Mapada UV-1200 ultraviolet spectrophotometer; COD cr The COD was determined using a Hach DR2800 analyzer (USA) and Hach TNT-823 reagent. Digestion was performed at 150℃ for 2 hours, followed by cooling to room temperature before measurement. crValue; ammonia nitrogen was determined using a Hach DR2800 analyzer (USA) with Hach TNT-831 reagent; the contents of phenolic compounds, ether compounds, halides (2-chloroethanol and ethyl 2-chloroethanol), alcohols, and lipids were determined using an Agilent GC-6890 gas chromatograph with an HP-5 column. The conversion rate of 2-chloroethanol and ethyl 2-chloroethanol was calculated using the formula: Conversion rate = (m 反应前 -m 反应后 ) / m 反应前 ×100%; BOD5 value was measured continuously for 5 days using BOD TrakII for the biochemical test.

[0052] Example 1

[0053] 1. Catalyst preparation process

[0054] 1.1 Preparation method of catalyst support

[0055] 100g of γ-Al2O3 (average particle size 40nm, specific surface area 62m²) was added. 2 The catalyst support was prepared by mixing 18g of Mg(NO3)2, 5g of nitric acid (68% by mass), and 52mL of water, followed by extrusion molding. The extruded product was dried at 40℃ for 48 hours and calcined at 840℃ for 2.5 hours.

[0056] 1.2 Catalyst Preparation Method

[0057] 100g of catalyst support was impregnated in a solution containing 18g of manganese nitrate, 32.3g of niobium oxalate, 4g of tartaric acid, and 100mL of water. The impregnation was carried out at 60℃ for 12h, and then dried at 60℃ for 24h to obtain the catalyst precursor. The catalyst precursor was calcined at 520℃ in air atmosphere for 5h to obtain 116.7g of heterogeneous catalyst with an active component content of 14.3% by weight. The XRD pattern showed that the catalyst support was a magnesium aluminum spinel and γ-Al2O3 structure, and manganese and niobium formed a manganese niobium composite oxide, which showed a characteristic peak near 2θ of 37°.

[0058] 2. Treatment methods for wastewater from waste lubricating oil hydroregeneration units

[0059] 2.1 Oil Removal Process

[0060] Wastewater from the waste lubricating oil hydrogenation regeneration unit (oil content: 2610 mg / L, 2-chloroethanol: 328 mg / L, 2-chloroethyl acetate: 1378 mg / L, COD) cr 248,000 mg / L, ammonia nitrogen: 1,896 mg / L, BOD5 / COD cr=0.06. Gas chromatography analysis of the organic composition of the wastewater revealed the following: chlorides accounted for 7.2% by weight of total organic pollutants, phenols for 6.5% by weight, ethers for 75.6% by weight, alcohols for 8.3% by weight, and esters for 2.4% by weight. This wastewater was mixed with 50 ppm of AP-type demulsifier for demulsification. The demulsified wastewater was then mixed with 10 ppm of the organic flocculant polyacrylamide (brand name JYN) and 20 ppm of the inorganic flocculant polyferric chloride for flocculation. After oil removal by filtration through a 0.5 μm filter membrane, the oil phase was returned to the waste lubrication hydrogenation unit, while the aqueous phase (pH less than 7) entered the wastewater pH adjustment tank. Oil content data before and after oil removal are shown in Table 1.

[0061] 2.2 pH Adjustment Process

[0062] Add a 1 mol / L sodium hydroxide solution to the aqueous phase, stir thoroughly, and adjust the pH of the wastewater to 8.5.

[0063] 2.3 Catalytic Wet Oxidation Process

[0064] (1) The effluent from the pH adjustment tank is mixed with soft water, COD cr The COD level dropped to 52160 mg / L, and the ammonia nitrogen level was 436 mg / L. After being mixed with high-pressure air at the bottom of the reactor, the wastewater entered a fixed-bed reactor packed with a multiphase catalyst. The reaction temperature was 180℃, the reaction pressure was 3.5 MPa, and the wastewater retention time was 2 hours. cr Ammonia nitrogen, conversion rates of 2-chloroethanol and ethyl 2-chloroethanol, and BOD5 / COD cr The results are shown in Table 1.

[0065] (2) The effluent from the catalytic wet oxidation process generated in step (1) is mixed with the effluent from the pH adjustment tank (volume ratio approximately 3:1), COD cr The concentration of COD decreased to 61140 mg / L, and the ammonia nitrogen concentration was 552 mg / L. The remaining operations and conditions were the same as in step (1). The COD after the reaction... cr Ammonia nitrogen, conversion rates of 2-chloroethanol and ethyl 2-chloroethanol, and BOD5 / COD cr The results are shown in Table 1.

[0066] Example 2

[0067] 1. Catalyst preparation process

[0068] 1.1 Preparation method of catalyst support

[0069] 80g of γ-Al2O3 (average particle size 40nm, specific surface area 62m²) was added. 2 / g), 23g of boehmite (specific surface area 266m²) 225g Mg(NO3)2, 5g nitric acid (68% by mass), and 52mL water were mixed and kneaded, then extruded. The extruded product was dried at 50℃ for 36 hours and calcined at 760℃ for 7 hours to obtain the catalyst support.

[0070] 1.2 Catalyst Preparation Method

[0071] 100g of catalyst support was impregnated in a solution containing 20g manganese nitrate, 10.5g niobium oxalate, 3.2g acetic acid, 1.8g tartaric acid, and 100mL water. The impregnation was carried out at 70℃ for 24h, followed by drying at 70℃ for 12h to obtain the catalyst precursor. The catalyst precursor was calcined at 430℃ in air for 3h to yield 112.3g of heterogeneous catalyst with an active component content of 10.9% by weight. Its XRD pattern showed that the catalyst support consisted of magnesium aluminum spinel and γ-Al₂O₃ structures, with manganese and niobium forming a manganese-niobium composite oxide, exhibiting a characteristic peak near 2θ = 37°.

[0072] 2. Treatment methods for wastewater from waste lubricating oil hydroregeneration units

[0073] 2.1 Oil Removal Process

[0074] Wastewater from the waste lubricating oil hydrogenation regeneration unit (oil content: 1865 mg / L, 2-chloroethanol: 416 mg / L, 2-chloroethyl acetate: 1053 mg / L, COD) cr 226350 mg / L, ammonia nitrogen: 1684 mg / L, BOD5 / COD cr =0.05. Gas chromatography analysis of the organic composition of the wastewater revealed the following: chlorides accounted for 7.4% by weight of total organic pollutants, phenols for 7.3% by weight, ethers for 71.9% by weight, alcohols for 9.3% by weight, and esters for 4.1% by weight. This wastewater was mixed with 100 ppm of AE-type demulsifier for demulsification. The demulsified wastewater was then mixed with 50 ppm of the organic flocculant polyacrylamide (brand name JYN) and 50 ppm of the inorganic flocculant polyferric sulfate for flocculation. After oil removal by filtration through a 2 μm filter membrane, the oil phase was returned to the waste lubrication hydrogenation unit, while the aqueous phase (pH less than 7) entered the wastewater pH adjustment tank. Oil content data before and after oil removal are shown in Table 1.

[0075] 2.2 pH Adjustment Process

[0076] Add 1 mol / L sodium hydroxide and 1 mol / L sodium carbonate solutions to the aqueous phase, stir thoroughly, and adjust the pH of the wastewater to 9.5.

[0077] 2.3 Catalytic Wet Oxidation Process

[0078] (1) The effluent from the pH adjustment tank is mixed with soft water, CODcr The COD level dropped to 55380 mg / L, and the ammonia nitrogen level was 458 mg / L. After being mixed with high-pressure air at the bottom of the reactor, the wastewater entered a fixed-bed reactor packed with a multiphase catalyst. The reaction temperature was 210℃, the reaction pressure was 2.8 MPa, and the wastewater retention time was 1.8 h. cr Ammonia nitrogen, conversion rates of 2-chloroethanol and ethyl 2-chloroethanol, and BOD5 / COD cr The results are shown in Table 1.

[0079] (2) The effluent from the catalytic wet oxidation process generated in step (1) is mixed with the effluent from the pH adjustment tank (volume ratio of approximately 1.8:1), COD cr The concentration of COD decreased to 76220 mg / L, and the ammonia nitrogen concentration was 673 mg / L. The remaining operations and conditions were the same as in step (1). The COD after the reaction... cr Ammonia nitrogen, conversion rates of 2-chloroethanol and ethyl 2-chloroethanol, and BOD5 / COD cr The results are shown in Table 1.

[0080] Example 3

[0081] 1. Catalyst preparation process

[0082] 1.1 Preparation method of catalyst support

[0083] 100g of pseudoboehmite (specific surface area 266m²) 2 8g of MgO powder, 5g of nitric acid (68% by mass), and 52mL of water were mixed and then extruded. The extruded product was dried at 60℃ for 24 hours and calcined at 810℃ for 4.5 hours to obtain the catalyst support.

[0084] 1.2 Catalyst Preparation Method

[0085] 100g of catalyst support was impregnated in a solution containing 27g manganese nitrate, 10.8g niobium oxalate, 0.8g acetic acid, 3.5g tartaric acid, and 100mL water. The impregnation was carried out at 80℃ for 8h, followed by drying at 60℃ for 24h to obtain the catalyst precursor. The catalyst precursor was calcined at 540℃ in air for 4h to yield 115.8g of heterogeneous catalyst with an active component content of 13.6% by weight. Its XRD pattern showed that the catalyst support consisted of magnesium aluminum spinel and γ-Al₂O₃ structures, with manganese and niobium forming a manganese-niobium composite oxide, exhibiting a characteristic peak near 2θ = 37°.

[0086] 2. Treatment methods for wastewater from waste lubricating oil hydroregeneration units

[0087] 2.1 Oil Removal Process

[0088] Wastewater from waste lubricating oil hydroregeneration unit (oil content: 3168 mg / L, 2-chloroethanol: 1537 mg / L, ethyl 2-chloroacetate: 871 mg / L, COD) cr 283600 mg / L, ammonia nitrogen: 1946 mg / L, BOD5 / COD cr =0.04. Gas chromatography analysis of the organic composition of the wastewater revealed the following: chlorides accounted for 7.8% by weight of total organic pollutants, phenols for 9.6% by weight, ethers for 72.3% by weight, alcohols for 7.1% by weight, and esters for 3.2% by weight. This wastewater was mixed with 400 ppm of SP-type demulsifier for demulsification. The demulsified wastewater was then mixed with 100 ppm of the organic flocculant polyacrylamide (brand name JYN) and 50 ppm of the inorganic flocculant polyferric chloride for flocculation. After oil removal by filtration through a 2 μm filter membrane, the oil phase was returned to the waste lubrication hydrogenation unit, while the aqueous phase (pH less than 7) entered the wastewater pH adjustment tank. Oil content data before and after oil removal are shown in Table 1.

[0089] 2.2 pH Adjustment Process

[0090] Add 1 mol / L sodium hydroxide and 1 mol / L sodium carbonate solutions to the aqueous phase, stir thoroughly, and adjust the pH of the wastewater to 10.

[0091] 2.3 Catalytic Wet Oxidation Process

[0092] (1) The effluent from the pH adjustment tank is mixed with soft water, COD cr The concentration of COD decreased to 68712 mg / L, and ammonia nitrogen decreased to 525 mg / L. After being mixed with high-pressure air at the bottom of the reactor, the wastewater entered a fixed-bed reactor packed with a multiphase catalyst. The reaction temperature was 190℃, the reaction pressure was 4.2 MPa, and the wastewater retention time was 2 hours. cr Conversion rates of 2-chloroethanol and ethyl 2-chloroethanol, BOD5 / COD cr The results are shown in Table 1.

[0093] (2) The effluent from the catalytic wet oxidation process generated in step (1) is mixed with the effluent from the pH adjustment tank (volume ratio approximately 3:1), COD cr The concentration of COD decreased to 69328 mg / L, and the ammonia nitrogen decreased to 605 mg / L. The remaining operations and conditions were the same as in step (1). The COD after the reaction... cr Ammonia nitrogen, conversion rates of 2-chloroethanol and ethyl 2-chloroethanol, and BOD5 / COD cr The results are shown in Table 1.

[0094] Example 4

[0095] 1. Catalyst preparation process

[0096] 1.1 Preparation method of catalyst support:

[0097] Same as in Example 1, but without the addition of Mg(NO3)2.

[0098] 2.2 Catalyst Preparation Method

[0099] Same as in Example 1, but without the addition of tartaric acid.

[0100] 2. Treatment methods for wastewater from waste lubricating oil hydroregeneration units

[0101] Same as in Example 1. The wastewater treatment results after step (2) are shown in Table 1.

[0102] Example 5

[0103] This embodiment is a comparative embodiment. The specific operation is the same as in embodiment 1, but step 2.2 is omitted. In step 2.1, the aqueous phase directly enters step 2.3. The wastewater treatment results after step (2) are shown in Table 1.

[0104] Example 6

[0105] Same as in Example 2, but Mg(NO3)2 in step 1.1 was replaced with calcium nitrate. The wastewater treatment results after step (2) are shown in Table 1.

[0106] Example 7

[0107] Same as Example 2, but the γ-Al2O3 and pseudoboehmite in step 1.1 are replaced with silica (average particle size 36 nm, specific surface area 182 m²). 2 / g). The wastewater treatment results after step (2) are shown in Table 1.

[0108] Example 8

[0109] Same as in Example 2, but with manganese nitrate replaced by ferric nitrate in step 1.2. The wastewater treatment results after step (2) are shown in Table 1.

[0110] Example 9

[0111] Same as in Example 2, but niobium oxalate in step 1.2 was replaced with 15.9g ammonium molybdate. The wastewater treatment results after step (2) are shown in Table 1.

[0112] Example 10

[0113] Same as in Example 2, but in step 1.1, the amount of boehmite used is 0g and the amount of Mg(NO3)2 used is 48g. The wastewater treatment results after step (2) are shown in Table 1.

[0114] Example 11

[0115] Same as in Example 2, but in step 1.1, the amount of boehmite used was 35g and the amount of Mg(NO3)2 used was 13g. The wastewater treatment results after step (2) are shown in Table 1.

[0116] Example 12

[0117] Same as in Example 2, but in step 1.2, the amount of manganese nitrate used is 2.5g and the amount of niobium oxalate used is 28g. The wastewater treatment results after step (2) are shown in Table 1.

[0118] Example 13

[0119] Same as in Example 2, but in step 1.2, the amount of manganese nitrate used is 25.5g and the amount of niobium oxalate used is 5g. The wastewater treatment results after step (2) are shown in Table 1.

[0120] Example 14

[0121] Same as in Example 2, but in step 2.1, the nonionic demulsifier was replaced with anionic demulsifier sodium alkyl sulfonate (brand name SAS-60). The wastewater treatment results after step (2) are shown in Table 1.

[0122] Example 15

[0123] Similar to Example 2, but in step 2.1, the inorganic flocculant was replaced with polyaluminum sulfate. The wastewater treatment results after step (2) are shown in Table 1.

[0124] Example 16

[0125] Similar to Example 2, but in step 2.1, the amount of organic flocculant used is 95 ppm and the amount of inorganic flocculant used is 5 ppm. The wastewater treatment results after step (2) are shown in Table 1.

[0126] Table 1

[0127]

[0128]

[0129] According to a preferred embodiment of the present invention, the COD of wastewater cr Removal rate ≥90%, conversion rate of 2-chloroethanol and ethyl 2-chloroacetate ≥98%, biodegradable BOD5 / COD ratio cr The concentration of nitrogen is increased from ≤0.1 to above 0.65, and the ammonia nitrogen content is reduced to below 200 mg / L. Furthermore, in a further preferred embodiment, the heterogeneous catalyst of the present invention does not contain precious metals and can efficiently treat wastewater, significantly reducing costs.

[0130] The inventors of this invention have also discovered that using at least two active components in the catalyst yields better treatment results than using only one. In particular, the use of two specific active components according to the preferred embodiment of this invention significantly improves the treatment effect, especially by further reducing the COD of the post-reaction wastewater and increasing the halide conversion rate and the effluent BOD5 / COD ratio. cr .

[0131] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for treating waste lubricating oil wastewater, characterized in that, The method includes: 1) Mix waste lubricating oil wastewater with demulsifier to demulsify; then mix the demulsified wastewater with flocculant to remove floating oil, so that the oil content in the wastewater after removing floating oil is less than 20% of the oil content in the waste lubricating oil wastewater. 2) Adjust the pH of the wastewater after oil removal to 7-14; 3) The effluent from step 2) is subjected to catalytic wet oxidation, wherein the effluent from catalytic wet oxidation is mixed with the effluent from step 2) to reduce the COD of the influent to the catalytic wet oxidation. cr Less than or equal to 100,000 mg / L; 4) Optionally, the effluent from step 3) may be subjected to biological treatment; The demulsifier is selected from nonionic demulsifiers; The catalytic wet oxidation method is as follows: in the presence of a heterogeneous catalyst and oxygen, the effluent from step 2) is subjected to catalytic wet oxidation; wherein, the heterogeneous catalyst includes a support and an active component, the active component is selected from oxides of Mn and oxides of Nb, and the content of oxides of Mn and Nb is such that the molar ratio of Mn to Nb is 1:(0.09-5); the support is selected from oxides of Mg and oxides of Al, and the content of oxides of Mg and Al is such that the molar ratio of Mg to Al is 1:(5.5-55); The waste lubricating oil wastewater contains 50-2000 mg / L of halides and has a COD of cr The concentrations are 100,000-300,000 mg / L, ammonia nitrogen content is 500-2000 mg / L, and BOD5 / COD ratio is [missing information]. cr The value is 0.02-0.08; Alternatively, the waste lubricating oil wastewater may be wastewater from a waste lubricating oil hydrogenation regeneration unit.

2. The method according to claim 1, wherein, Based on the weight of the waste lubricating oil wastewater, the weight dosage of demulsifier is 50~500ppm, and the weight dosage of flocculant is 10~400ppm. And / or, the nonionic demulsifier is selected from at least one of SP type demulsifier, AP type demulsifier, AE type demulsifier and AR type demulsifier; And / or, in step 2), hydroxides are used to adjust the pH of the wastewater after oil removal to 7-14; And / or, the volume ratio of the effluent from the catalytic wet oxidation to the effluent from step 2) is 0.5 to 5.

3. The method according to claim 2, wherein, The hydroxide is selected from at least one of sodium hydroxide, potassium hydroxide, and calcium hydroxide; And / or, the volume ratio of the effluent from the catalytic wet oxidation to the effluent from step 2) is 0.6 to 4.

4. The method according to claim 1, wherein, The flocculant includes an iron-containing flocculant.

5. The method according to claim 4, wherein, The flocculant is selected from organic flocculants and iron-containing inorganic flocculants with a weight ratio of 1:(0.1~10).

6. The method according to claim 5, wherein, The organic flocculant is selected from at least one of polyacrylamide, sodium polyacrylate, polyvinylpyridine salt, polyethyleneimine, and sodium carboxymethyl cellulose.

7. The method according to claim 5, wherein, The iron-containing inorganic flocculant is selected from at least one of polyferric chloride, polyferric sulfate, polyferric chloride sulfate, and polyphosphoric ferric chloride.

8. The method according to claim 1, wherein, In step 1), the oil content in the wastewater after oil removal is ≤200mg / L; And / or, in step 2), the pH value of the wastewater after oil removal is adjusted to 8~12.

9. The method according to claim 1, wherein, The conditions for the catalytic wet oxidation include: a reaction temperature of 120~250℃ and a reaction pressure of 1~7MPa.

10. The method according to claim 9, wherein, The conditions for the catalytic wet oxidation include: a reaction temperature of 160~220℃ and a reaction pressure of 2.5~4.5MPa.

11. The method according to any one of claims 1, 9, or 10, wherein, The conditions for the catalytic wet oxidation also include: influent COD cr The concentration is 20,000~100,000 mg / L; the wastewater retention time is 0.5~5 h.

12. The method according to claim 11, wherein, The conditions for the catalytic wet oxidation also include: influent COD cr The concentration is 40,000~80,000 mg / L; the wastewater retention time is 1~3 hours.

13. The method according to claim 1, wherein, Based on the total weight of the heterogeneous catalyst, the content of the support is 85-95% by weight, and the content of the active component is 5-15% by weight. And / or, based on the total weight of the heterogeneous catalyst, the content of noble metals in the heterogeneous catalyst is ≤0.5% by weight; And / or, in the XRD pattern of the heterogeneous catalyst, at 2θ=37 o A characteristic peak is present at ±0.

2.

14. The method according to claim 1, wherein, The active components are selected from oxides of Mn and oxides of Nb, and the contents of oxides of Mn and oxides of Nb are such that the molar ratio of Mn to Nb is 1:(0.1-3). And / or, the carrier is selected from oxides of Mg and oxides of Al, and the content of oxides of Mg and Al is such that the molar ratio of Mg to Al is 1:(10-25).

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